Page 51 - 2020 Interconnect Innovations eBook

Cladding is a two-step process composed of roll reduction and diffusion. During roll reduction, the material thickness is reduced by 75%, which creates four times the amount of surface area at the interface. This increase in material does not increase the width of the material, but rather adds to the length of the strip. Within the new area that is created during roll reduction, an atomic connection is formed between the joined metals. This happens because the oxides are dispersed, creating a true atom-to-atom connection between the layers.
In the second phase of cladding, the layered atomic connections are diffused together through continuous heat treating in very controlled conditions. This part of the process supplies energy to drive diffusion and alloying between the two layers. After the bond is sintered, the metal strip is then processed using traditional methods, such as rolling, annealing, and forming. The end result is a material with a true metallurgical bond that is purely fused together.
Cladding vs. Electroplating for Greater Wear Resistance
Currently, electroplated silver is the most commonly used connector material for EV charging terminals. However, when used in faster charging systems, it doesn’t offer the material hardness needed to resist wear because the electroplating process simply coats a material while cladding metallurgically bonds two or more materials together. As such, the grain paths in electroplated materials are small and porous compared with the large, dense grains in clad metal, which are much longer and more effective in slowing diffusion to stabilize performance at elevated temperatures.
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» A fully dense microstructure across the entire clad thickness range provides stable performance at elevated temperatures over the life of connectors made with Materion’s iON EV clad material.
iON EV Clad Material Addresses EV Connection Challenges
Industry experts are finding ways to increase the number of EV battery charging cycles along with power density and lifetime performance, which makes the need for the material and contact surface to survive over time even more critical. Equally important as using the right processing method is selecting a material combination that will address the unique needs of an EV connector application.
The engineering team behind the new iON EV material solution utilized a silver-based clad alloy to create a reliable replacement for traditional silver solutions. By combining silver and other metals via cladding to form a metallurgical bond, they ultimately designed the alloy to address multiple charger terminal connector challenges — from insertion force to wear to conductivity — with just one material solution. The diagram below captures the concept of optimizing and balancing the attributes of different metals in a single solution that wouldn’t be possible with just one material.
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